Special Report

10 Deadliest Diseases in the World


Disease is responsible for by far the most deaths worldwide. The first eight of the 12 leading causes of death globally are all diseases, and only two of the next four — road injury and preterm birth — are not diseases. Noncommunicable diseases accounted for 68% of the 56 million deaths in 2012. Three in every 10 deaths worldwide, or 17.5 million deaths, were caused by cardiovascular diseases.

24/7 Wall St. reviewed the 10 diseases that caused the most deaths in 2012. Ischaemic heart disease is the leading global killer, with 7.4 million deaths. Tuberculosis, which was attributed to 900,000 deaths worldwide, rounds out the top 10.

Cardiovascular illnesses, cancers, diabetes, and chronic lung diseases are the four major noncommunicable diseases. Many forms of these diseases can be prevented, if not cured, and all can be treated. Nearly three-quarters of deaths from these noncommunicable diseases occurred in low- and middle-income nations. This high proportion means poor access to treatment is by far the largest driver of death from these diseases.

Click here to see the 10 deadliest diseases in the world.

The poverty rate in nearly every region of the world has declined by half since 1990 — except in sub-Saharan Africa, where more than 40% of the population lives in extreme poverty, a more modest improvement from previous decades. HIV/AIDs, one of the world’s deadliest diseases and the deadliest communicable disease, is a major cause of death in sub-Saharan Africa. The vast majority of all people globally with HIV live in the region. According to the World Health Organization, the incidence of HIV decreased due to increased availability of treatment.

The nature of a disease can vary geographically. For example, while the death rate from COPD is similar in lower- and upper-middle income countries, the causes of the disease are different. In lower to middle income countries, the primary cause of COPD is exposure to air pollution. In upper-middle income countries, on the other hand, the primary cause of COPD is tobacco use.

Similarly, risk factors, which may not directly cause a disease but can increase the risk of being sick, vary across income groups. Alcohol and tobacco use, obesity, and high blood pressure — which are associated with heart disease and cancer — are the greatest risk factors in high-income countries. These risk factors account for most healthy years of life lost. In low-income countries, by contrast, malnutrition, starvation, and suboptimal breastfeeding drive mortalities from disease.

Another differentiating factor between low- and high-income countries is age. For example, the likelihood of cardiovascular disease goes up with age. For this reason, the incidence of these heart diseases tends to be higher in wealthier countries, where people live longer.

To identify the world’s deadliest diseases, 24/7 Wall St. reviewed the total number of deaths in 2012 from diseases estimated by the World Health Organization. The estimated number of deaths in 2000 also came from the WHO.

These are the world’s deadliest diseases.

10. Tuberculosis
> Deaths in 2012:
900,000 million
> Deaths in 2000: 1.3 million
> Share of global deaths: N/A

Nearly 1 million people died of tuberculosis in 2012, down from 1.3 million in 2000. Overall, tuberculosis is the 12th largest cause of death worldwide, and among diseases the 10th largest cause of death. According to the WHO, the relatively low quality and amount of data available, while steadily improving, mean the actual number of deaths due to TB is likely far higher. There were 9.6 million new cases of TB in the world in 2014, the vast majority of which were reported in Southeast Asia, Western Pacific, and African regions.

9. Hypertensive heart disease
> Deaths in 2012:
1.1 million
> Deaths in 2000: 0.8 million
> Share of global deaths: 2.0%

Hypertensive heart disease refers to heart problems caused by high blood pressure. High blood pressure is an underlying factor in many diseases, and is responsible for 58% of all cardiovascular deaths. Along with stroke, ischaemic heart disease, and other conditions, cardiovascular disease is the leading cause of death worldwide. Medication and lifestyle changes such as physical activity and healthy eating can reduce high blood pressure. Still, many people are unaware of their blood pressure levels and as a result hypertension often goes undetected. Hypertensive heart disease is one of the leading causes of death in upper-middle and high-income countries, where it is responsible for 20 deaths per 100,000 people annually, in line with motor vehicle fatalities.

8. Diabetes mellitus
> Deaths in 2012:
1.5 million
> Deaths in 2000: 1 million
> Share of global deaths: 2.7%

People with diabetes can lead a long and healthy life when treated with medication and lifestyle changes. Despite this, the disease was responsible for 1.5 million deaths worldwide in 2012, up 50% from 1 million in 2000. There are several types of diabetes, but type 2 diabetes is by far the most common, accounting for about 90% of all diabetes cases. Although physical activity and a healthy diet can significantly lower the risk of developing type 2 diabetes, reports of the disease have been increasing worldwide, reflecting the growing prevalence of obesity. Moreover, type 2 diabetes, which was previously rare among children, is becoming increasingly more common among overweight youths. Diabetes is also most common in the Eastern Mediterranean region.

7. Diarrhoeal disease
> Deaths in 2012:
1.5 million
> Deaths in 2000: 2.2 million
> Share of global deaths: 2.7%

Diarrhea can be treated with clean water, sugar, salt, and zinc tablets. Yet, while entirely preventable and fully treatable once contracted, diarrhoeal disease killed 1.5 million people in 2012, making it the seventh leading cause of death in the world. Further, it is the second leading cause of death among young children, killing an estimated 760,000 children under the age of five annually. Diarrhoea is usually a symptom of an infection in the intestinal tract, a very common condition in areas with unsafe drinking water, especially water contaminated with human or animal feces. Angola, Somalia, Chad, Central African Republic, and Sierra Leone report the highest death tolls among children from diarrhoeal disease.

> Deaths in 2012:
1.5 million
> Deaths in 2000: 1.7 million
> Share of global deaths: 2.7%

Like a few other deadly diseases, the death toll from HIV/AIDS fell from the 2000 estimate of 1.7 million to 1.5 million in 2012. In the mid-2000s, due in part to the Trade-Related Aspects of Intellectual Property Rights (TRIPS) agreement, the price of certain drugs dropped dramatically — antiretroviral medicines used to treat HIV/AIDS have become 100 times more affordable. Cheaper, high-quality generic drugs are essential for treating HIV/AIDS, particularly in sub-Saharan Africa, which is home to seven out of every 10 people with HIV worldwide.

5. Trachea, bronchus, lung cancers
> Deaths in 2012:
1.6 million
> Deaths in 2000: 1.2 million
> Share of global deaths: 2.9%

In many places around the world, death from disease is largely due to lack of treatment and inadequate health services. Lung cancer can be treated, but there is no cure, which accounts for at least part of the high global death toll. The incidence of lung cancer is roughly equal to the mortality rate from the disease. And while there have been great strides in cancer treatment, and death tolls from many types of cancer have dropped substantially, lung cancer mortality has improved only slightly from 2000. Among men, deaths from lung cancer fell by 4% globally and by a much larger 19% among men in high-income OECD countries. Among women, lung cancer deaths increased from 2000 through 2012.

4. Lower respiratory infections
> Deaths in 2012:
3.1 million
> Deaths in 2000: 3.5 million
> Share of global deaths: 5.5%

Bronchitis is the most common respiratory infection. Generally, however, lower respiratory infections are not as clearly defined as other deadly diseases, which hinder the ability to gain understanding of the full scope of the disease. This can also hurt the efforts of advocacy groups and organizations working to lower the incidence of these diseases. People with asthma or sinusitis may develop an acute respiratory infection, but often the underlying cause is unknown. Air pollution is a major contributor to the incidence of respiratory illnesses. While in many high-income countries air pollution has decreased considerably, elsewhere emissions and the levels of harmful particulate matter have increased dramatically. In South and East Asia, the increase in air pollution is largely due to population growth. Approximately three in every four people globally were exposed to potentially hazardous pollution in 2012.

> Deaths in 2012:
3.1 million
> Deaths in 2000: 3.1 million
> Share of global deaths: 5.6%

Chronic obstructive pulmonary disorder refers to any chronic lung disease that disrupts the airflow to the lungs. The primary risk factors of COPD are tobacco smoking and air pollution. The disease is typically diagnosed in individuals 40 years old or older, worsens over time, and is not curable. The primary causes of COPD vary by geography. In high- and middle-income countries, tobacco is the main risk factor, while in low-income countries exposure to pollution, particularly from indoor sources like low quality kitchen facilities, is the main risk factor. An estimated 64 million people worldwide have COPD, and 3.1 million died from it in 2012. While this is the same death toll as in 2000, deaths are expected to increase in the future.

2. Stroke
> Deaths in 2012:
6.7 million
> Deaths in 2000: 5.7 million
> Share of global deaths: 11.9%

Strokes are caused by an interruption of the blood supply to the brain. The temporary lack of oxygen and nutrients damage the brain tissue, and in some cases this can be fatal. Like many cardiovascular diseases, the risk of stroke can often be reduced. A healthy diet, frequent exercise, monitoring blood pressure levels, and abstaining from tobacco use will lower the likelihood of stroke. Stroke is the leading cause of death in upper-middle income countries, where it causes 126 deaths per every 100,000 people. The disease is even more common in low- and middle-income countries, where three out of every four cardiovascular mortalities are reported.

1. Ischaemic heart disease
> Deaths in 2012:
7.4 million
> Deaths in 2000: 6.0 million
> Share of global deaths: 13.2%

Across the globe, no disease causes more deaths than ischaemic heart disease. Ischemia is a condition in which the heart arteries narrow, and the flow of blood and oxygen to the heart becomes limited. Ischaemic heart disease, also known as coronary heart disease, accounts for more than two in every five cardiovascular deaths worldwide. Heart diseases can often be prevented. Healthy eating, physical activity, and abstaining from tobacco use can lower an individual’s risk of cardiovascular disease. The highest cardiovascular mortality rates are found in Eastern European countries. In Turkmenistan, 712 people per 100,000 die from heart diseases such as ischaemic heart attack and stroke, the highest cardiovascular death rate of any country. Across the globe, 7.4 million people died of ischaemic heart disease in 2012, up from 6 million in 2000.

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